function  ROIlines(xROI,yROI)

    line([xROI(1) xROI(end)],[yROI(1) yROI(1)])
    line([xROI(1) xROI(1)],[yROI(1) yROI(end)])
    line([xROI(end) xROI(end)],[yROI(1) yROI(end)])
    line([xROI(1) xROI(end)],[yROI(end) yROI(end)])
end